Deposition of SiOx diffusion barriers on flexible packaging materials by PECVD

This study focuses on the water vapor permeability of plasma enhanced chemical vapor deposited (PECVD) silicon oxide (SiOx) films. A batch reactor equipped with a 2.45 GHz slot antenna plasma source and a 13.56 MHz-biased substrate holder, was used to conduct the experiments. The remote microwave and the direct radio frequency plasma source can be operated separately or in dual mode. An oxygen plasma was generated and hexamethyldisiloxane (HMDSO) used as monomer. The SiO2-like films were deposited onto 12 μm PET film. An increase of RF-power input, oxygen-to-monomer flow rate ratio, layer thickness or decrease of process pressure was found to enhance the gas barrier performance. Compared to uncoated PET films, a maximum reduction of more than a factor of 150 has been achieved for water vapor transmission rate.